Figure 5.

Chronic morphine upregulates PLA₂ activity. A, Dose–response relationship for AACOCF3 antagonism of DAMGO-mediated inhibition of IPSCs in neurons of the saline group (open circles) and of the morphine group (filled circles). n = 6–12 cells for each data point. B, Similar experiments of AACOCF3 antagonism but in the presence of KT5720 for both the saline group (n = 8–11) and the morphine group (n = 5 for each AACOCF3 dose), showing AACOCF3 antagonism of PLA₂-mediated DAMGO inhibition (normalized). C, D, Representative lanes and group data of Western blots for cPLA₂ and phosphorylated cPLA₂ as well as for β-actin in NRM tissues from placebo (n = 6) and morphine pellet-implanted (n = 9) rats (C) and from saline (n = 5)- and morphine (n = 5)-injected rats (D). Data of percentage changes were normalized to the expression of β-actin. The molecular mass was 95 kDa for cPLA₂ and phosphorylated cPLA₂. *p < 0.05, **p < 0.01.